This invention is directed to various innovations in snowmobile design, including a drive train that reduces the center of gravity and/or increases mass centralization of the snowmobile.
Snowmobile design has incrementally moved towards more powerful motors, with a resulting increase in the weight of the machines due to the larger motor and corresponding support structure. Frequently, increased weight results in a higher center of gravity of the snowmobile. Increased weight and increased center of gravity can have a detrimental affect on the ride quality and handling characteristics of the snowmobile.
Handling, cornering and ride quality are largely dependent upon the front suspension system of the snowmobile. It is common practice to suspend the skis of a snowmobile independently by means of respective strut type suspensions. It is desirable to provide some form of stabilizer or sway bar arrangement interconnecting the front skis to reduce the amount of leaning that occurs during cornering of the snowmobile. Due to the rough and sometimes uncertain terrain over which snowmobiles are ridden, it is desirable that the stabilizer arrangement be positioned so that it will be protected if unexpected objects are encountered, such as disclosed in U.S. Pat. No. 4,690,234 (Takada).
U.S. Pat. No. 4,489,954 discloses an anti-roll mechanism that includes a torsion bar supported by the body that is connected to the skis for torsion loading upon independent movement of the skis relative to the body. The connection between each of the skis and the torsion bar is such that the torsion bar is loaded by the pivotal movement of the skis about their steering axes for providing a self-centering force on the skis.
U.S. Pat. No. 4,671,521 (Talbot, et al) discloses a snowmobile ski suspension including upper and lower transverse suspension arms vertically spaced and each having an outboard end articulated to a ski spindle and an inboard end articulated to a fixed mounting on the frame of the snowmobile. The upper and lower transverse suspension arms define a parallelogram linkage for guiding the spindle to move generally vertically with respect to the snowmobile.
U.S. Pat. No. 5,029,664 (Zuwalski) discloses a suspension system with a geometry that includes upper and lower suspension linkages of predetermined lengths in cooperation with a spindle of a predetermined length for eliminating lateral movement of the skis during suspension travel. The respective linkages and spindles are interconnected by ball joints at predetermined locations in such a manner that during deflection of the suspension system, a ski attached to the lower end of the spindle moves substantially in a line parallel to a vertical plane which contains the longitudinal axis of the snowmobile.
What is needed is a snowmobile design that provides a high power-to-weigh ratio while maintaining optimum handling characteristics and ride quality.
The present invention is directed to various innovations in snowmobile design. In one embodiment, the snowmobile includes a modular front suspension system and a stabilizer assembly. In another embodiment, the frame structure includes a lightweight frame structure. In yet another embodiment, the snowmobile includes a drive train that reduces the center of gravity. Finally, all of these features are combined on a single snowmobile.
The present snowmobile assembly includes a snowmobile chassis having a motor compartment at a front portion and an endless belt channel at a rear portion. A motor is located substantially in the motor compartment substantially in front of the endless belt channel. The motor includes at least one exhaust port arranged toward a rear portion of the snowmobile chassis and/or at least one fuel control mechanism arranged toward a front portion of the snowmobile chassis. By arranging the at least one exhaust port toward the rear portion of the snowmobile chassis, the snowmobile assembly has greater mass centralization and/or a lower center of gravity than it would otherwise have if the exhaust port was arranged toward the front portion of the snowmobile chassis. Similarly, by arranging the at least one fuel control mechanism toward the front portion of the snowmobile chassis, the snowmobile assembly has greater mass centralization and/or a lower center of gravity than it would otherwise have if the exhaust port was arranged toward the front portion of the snowmobile chassis. A drive train couples the motor to an endless belt drive shaft located in the endless belt channel. An endless belt is located in the endless belt channel coupled to the endless belt drive shaft.
The present invention is also directed to a chassis for a snowmobile having an endless belt drive system. The chassis includes a plurality of front structural members defining a motor compartment. Front suspension system mounting locations are positioned on distal ends of two or more of the front structural members. A pair of independent, rear structural members are rigidly connected to the front structural members and extend rearwardly from the motor compartment on opposite sides of an endless belt channel. A protective shell extends between the pair of rear structural members and over the endless belt channel. In one embodiment, the protective shell comprises a lightweight, resin based material that transfers substantially no loads between the pair of rear structural members. The snowmobile chassis further includes a rear suspension system extending between the pair of rear structural members. The rear suspension system transfers substantially all loads between the pair of rear structural members.
In one embodiment, the snowmobile chassis includes a motor located in the motor compartment. The motor has at least one carburetor positioned on a first side of the motor adjacent to the front suspension system mounting locations and an exhaust port positioned on a second side of the motor.
The present invention is also directed to a snowmobile chassis having a motor compartment and an endless belt channel. A motor is located in the motor compartment. The motor has at least one carburetor positioned on a first side of the motor adjacent to a front suspension system and an exhaust port positioned on a second side of the motor. The motor has a drive clutch. A driven pulley is located on a gearbox that is located adjacent to the endless belt channel. An endless belt drive shaft is located in the endless belt channel and mechanically coupled directly to the gearbox. A drive belt mechanically couples the drive clutch to the driven pulley. A torque arm connects the driven pulley to the snowmobile chassis.